Another interesting message from cgminer, which is rare however. I've found very good explanation on one of the forums from the person with nickname ckolivas. The original post can be found here. I'd like to quote this post and add some personal comments.
Quote: "
When cgminer sends shares via stratum, it does not send the share and then wait for the response as this might slow down the sending of other shares. This means that the response back from the pool is processed separately from the share submission (to make the most of a truly multithreaded environment). However there is never a guarantee that the responses come back in the same order you send them. So cgminer stores a copy of each share as it sends it to the server in its own local database of submitted shares. When it gets a response back about that share from the pool, it deletes the copy of that share. Now stratum is meant to be an uninterrupted connection to the pool, and if you lose that connection, it is assumed that your "session" is no longer valid. So if you send some shares and get disconnected before you get a response, cgminer has to assume that those shares have been lost - otherwise it may end up keeping copies of heaps of shares that it will never get a response to and wastes memory. If you manage to reconnect, sometimes the pool will actually tell you "oh by the way those shares are ok" - however cgminer has now thrown out the record of what those shares were and can only say that the pool said a share was accepted or rejected. Then cgminer just says it's an "untracked share"." (c) ckolivas
I personally think, that when pool server start to get some performance problems(hardware or load problems) this things start to emerge. Also it can be on your side, because of your switch, network adapter or internet service provider. I have personally experienced these messages when pool operator was in process of adding separate server to cope with growing pool size. When he finished I didn't see these messages anymore.
Summary.
Find out whether your pool has some HW resources problem or it is under maintenance. If you experience these messages for several days and have no information from the pool owners then you should consider to find another pool or network setup that gives you more reliable connection.
When cgminer sends shares via stratum, it does not send the share and then wait for the response as this might slow down the sending of other shares. This means that the response back from the pool is processed separately from the share submission (to make the most of a truly multithreaded environment). However there is never a guarantee that the responses come back in the same order you send them. So cgminer stores a copy of each share as it sends it to the server in its own local database of submitted shares. When it gets a response back about that share from the pool, it deletes the copy of that share. Now stratum is meant to be an uninterrupted connection to the pool, and if you lose that connection, it is assumed that your "session" is no longer valid. So if you send some shares and get disconnected before you get a response, cgminer has to assume that those shares have been lost - otherwise it may end up keeping copies of heaps of shares that it will never get a response to and wastes memory. If you manage to reconnect, sometimes the pool will actually tell you "oh by the way those shares are ok" - however cgminer has now thrown out the record of what those shares were and can only say that the pool said a share was accepted or rejected. Then cgminer just says it's an "untracked share"." (c) ckolivas
I personally think, that when pool server start to get some performance problems(hardware or load problems) this things start to emerge. Also it can be on your side, because of your switch, network adapter or internet service provider. I have personally experienced these messages when pool operator was in process of adding separate server to cope with growing pool size. When he finished I didn't see these messages anymore.
Summary.
Find out whether your pool has some HW resources problem or it is under maintenance. If you experience these messages for several days and have no information from the pool owners then you should consider to find another pool or network setup that gives you more reliable connection.